DIY Audio Projects Forum

Welcome to the DIY Audio Projects Message Forum. Use these forums to discuss Hi-Fi audio and to share your DIY Audio Projects. Registration is free and required to post messages and view the file attachments. Registration will only take a minute and registered users do not see any advertisements. After you have completed the online registration process, check your email (including spam/junk folder) for the verification email to activate your account. New members are under moderation - so your posts will not be visible until approved by a moderator. See the Read Me 1st, Forum RULES and Forum FAQ to get started on the forum.

After building and selling a number of Mimic MM and MM_MC phono preamps, all based on Oddwatt's great design, I have here a Carbon film resistor version. All other builds use metal film 1/2W resistors. Carbon film 1W resistors have been used in a few of my tube power amps and the sound is rich and mellow. Here 1/4W fine carbon film resistors are used.

To make this build even more different with MKT caps I have also used Polypropylene and Russian Mil. PIO caps. The large red caps in the image above are 4uf PIO snubbed with 220nF polies. The usual OPA2134 chip and mil. spec. socket are used. Silver plated fine wire wrap wire is used for the short hookups. PS and amp exist on a 5cm square of vero-board. WBT silver solder holds it all together.

I had hoped this preamp would run from a single 9V battery but in the end two 9V batteries were required. This should provide 100hours of play between battery changes. A battery test point is at the front and an earth lug on the side. Initial test show good promise with a rich and warm sound from (at this point) limited listening. Interestingly on a short A/B test it sounded similar to my LM833 based two stage MM preamp. Both have great warmth.

Attachment:

P8133628 (800x598).jpg

Attachment:

P8133629 (800x570).jpg

Attachment:

P8133630 (800x599).jpg

Attachment:

P8133627 (800x568).jpg

This post has a file attachment. Please login or register to access it. Only Registered Members may view attached files.

Hi Mark, I tried carbon films in one as well but liked the metal film ones better. The carbon film ones seemed to take some of the sizzle out of my system. Nice to listen to but not my style. This design seems to perform far better than it should. Simple as are most of mine, but carefully tweaked for best performance. I have been getting requests to build them. It seems that one person hears one and shows another and on it goes. Mine all use AC power though like in the original project. I'm going to have to order a bunch of parts to keep up. As for comparisons with some of my other preamps...I like the sound better than the Simaudio Moon LP3 and it is nearly as quiet (that one is amazinly quiet), they are not as nice as the several versions of the Groove, but then the tube ones are much more sophisticated, the ones built into things here (three Marantz, and a Hafler) are not in the same league as either the Mimic or Groove.

G'day mate, now I'm quite confused! I seem to recall that you've had poor results and oscillation? with the LM833 in the past. Do I have that wrong? I've used LM833 many times in the past with no issues at all, although I prefer to use 'ON SEMI' types if possible as they appear to be free of possible issues from my reading on the 'net. Regards, Felix.

G'day mate, now I'm quite confused! I seem to recall that you've had poor results and oscillation? with the LM833 in the past. Do I have that wrong? I've used LM833 many times in the past with no issues at all, although I prefer to use 'ON SEMI' types if possible as they appear to be free of possible issues from my reading on the 'net. Regards, Felix.

The only time I can remember oscillation is with my first Mimic. I put a nF cap on the input and she sang. Cut the cap away and all was good. Only did it once and it was my very first Mimic.

Who is online

Users browsing this forum: No registered users and 5 guests

You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot post attachments in this forum